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Re: [Xen-devel] hvm save restore support

On Wed, Dec 13, 2006 at 02:09:08PM -0600, Anthony Liguori wrote:
> Zhai, Edwin wrote:
> >ian/keir,
> >this is the new hvm save/restore patch on top of r12898.
> >although not tested intensively across all platform combinations, general
> >linux/windows guest works fine W/O break anything.
> >  
> So what are the plans for merging save/restore?
> If possible, it would be nice to see some changes first.  For instance, 
> it seems a real shame to not use the existing QEMU format.  There's 
> really no technical reason why a saved Xen VM shouldn't be loadable in 
> QEMU (and vice versa).
regarding HVM save/restore format compatibility, PV domain has higher priority 
then qemu. if saved HVM guest can be loaded in qemu, HVM's format should be 
totally different with PV, which break our policy.
for HVM guest we only use the qemu's device part, so only device part's format 
are kept. it's reasonable.
> Perhaps we should also considering using a higher level kernel interface 
> too?   2.6.20 is already going to contain a kernel interface for 
i'm not familiar with this kernel interface, but seems it is called by guest 
itself.  if so, this interface looks like OS suspend/resume that has different 
meaning of guest save/restore(transparent to guest).
> transferring guest state (for KVM).  It would be nice if we didn't keep 
> introducing Xen specific things to our qemu fork so that we could 
> eventually get this stuff upstream.
take it easy. HVM save/restore only add small change to qemu fork -- just make 
it get the save notification and take proper action.  my patch partly revert a 
PCI patch for work around that maybe mislead you.

BTW, with introduction of driver domain in future, the issues of qemu 
compatibility and changes should be nothing.
> Regards,
> Anthony Liguori

best rgds,

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